Re: [U-Boot] gpio: Question about gpio_set_value() implementation in spear_gpio.c

On 19.06.2013 16:01, Axel Lin wrote:

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• writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
  

• if (value)
  

•         writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
  

• else
  

•         writel(0, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
  

You might want to use clrbits_le32() and setbits_le32() here, no?

Honestly, I ask this because I cannot find the detail datasheet for the gpio control of this device. ( Just found the code looks strange).

Usually we can use clrbits_le32() and setbits_le32() helpers to set/clear register bits. But if the only meaningful bit is "1 << gpio", simply use "write 1 << gpio" and "write 0" saves a register read operation.

So maybe Stefan or someone from ST can provide the information about gpio control on this hardware.

I honestly have no idea how I tested this GPIO driver. That was too long ago. And I don't have the time to dig out the hardware to do some re-testing. But the code definitely looks wrong, so thanks for catching this. Let's wait what the ST engineers have to comment here.

Thanks, Stefan